Technical Field
The present disclosure generally relates to depth camera systems and, more particularly, depth camera systems that employ coded structured light.
Description of the Related Art
There are many types of depth camera technologies, including, for example, time of flight, passive and active stereo, and structured light. Such technologies enable a depth camera system to determine depth values for a scene observed by the system. For example, each depth value may be representative of a distance from the depth camera system to a particular object contained within the scene.
Systems that perform time of flight techniques rapidly pulse a light source and determine a delay between emission of the light and reception of light reflected from various locations in the scene. A system that performs time of flight techniques typically requires a complex, custom imaging sensor.
Systems that perform stereo techniques match corresponding image points respectively seen by plural cameras. Such correspondence detection requires significant processing, particularly when applied to image regions that are homogenous in color or intensity. Thus, in order to perform well with respect to untextured scenes, depth camera systems often augment stereo techniques by using a projected light pattern, also known as active stereo. Rectifying the images can simplify processing by allowing the correlation to occur along a linear shift called the epipolar line. However, stereo techniques still include a significant processing time and cost.
Structured light systems typically include a camera and a projector. The projector projects a pattern of light (i.e., structured light) towards the scene. The system compares the locations of certain features of the pattern in a captured image of the illuminated scene with locations of the features in a reference image to determine disparities. Such disparities can be used to determine depth at each location. However, for complex patterns, detection of pattern features and/or matching of detected features with reference features can be computationally expensive, similar to stereo techniques.
Other structured light techniques exist, as well. For example, temporal structured light methods use a sequence of light patterns emitted by a programmable projector to provide accurate range maps. However, temporal techniques typically require the scene to be remain stationary.